Correlation between serum hepcidin levels and hemoglobin concentrations. We used 25 MM patient serum samples for which hemoglobin content and serum hepcidin concentration were previously measured.^6,10,11  (A) Serum hepcidin levels in MM patients (n = 25) were significantly higher than in healthy individuals (n = 15). Boxes represent median and 25-75 percentiles, and whiskers represent 10 and 90 percentiles. Circles are the outliers. Statistical significance was determined with the Mann-Whitney rank-sum test; *P < .01, compared with normal serum. (B) Patients with normal renal function (n = 16) were included to investigate the relationship between serum hepcidin levels and hemoglobin concentrations. Hemoglobin concentrations and serum hepcidin inversely correlate (R² = 0.4277, P = .006, Pearson correlation).